/***
 * ASM: a very small and fast Java bytecode manipulation framework
 * Copyright (c) 2000-2011 INRIA, France Telecom
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the copyright holders nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.springframework.asm;

/**
 * A constant pool item. Constant pool items can be created with the 'newXXX'
 * methods in the {@link ClassWriter} class.
 *
 * @author Eric Bruneton
 */
final class Item {

	/**
	 * Index of this item in the constant pool.
	 */
	int index;

	/**
	 * Type of this constant pool item. A single class is used to represent all
	 * constant pool item types, in order to minimize the bytecode size of this
	 * package. The value of this field is one of {@link ClassWriter#INT},
	 * {@link ClassWriter#LONG}, {@link ClassWriter#FLOAT},
	 * {@link ClassWriter#DOUBLE}, {@link ClassWriter#UTF8},
	 * {@link ClassWriter#STR}, {@link ClassWriter#CLASS},
	 * {@link ClassWriter#NAME_TYPE}, {@link ClassWriter#FIELD},
	 * {@link ClassWriter#METH}, {@link ClassWriter#IMETH},
	 * {@link ClassWriter#MODULE}, {@link ClassWriter#PACKAGE},
	 * {@link ClassWriter#MTYPE}, {@link ClassWriter#INDY}.
	 * <p>
	 * MethodHandle constant 9 variations are stored using a range of 9 values
	 * from {@link ClassWriter#HANDLE_BASE} + 1 to
	 * {@link ClassWriter#HANDLE_BASE} + 9.
	 * <p>
	 * Special Item types are used for Items that are stored in the ClassWriter
	 * {@link ClassWriter#typeTable}, instead of the constant pool, in order to
	 * avoid clashes with normal constant pool items in the ClassWriter constant
	 * pool's hash table. These special item types are
	 * {@link ClassWriter#TYPE_NORMAL}, {@link ClassWriter#TYPE_UNINIT} and
	 * {@link ClassWriter#TYPE_MERGED}.
	 */
	int type;

	/**
	 * Value of this item, for an integer item.
	 */
	int intVal;

	/**
	 * Value of this item, for a long item.
	 */
	long longVal;

	/**
	 * First part of the value of this item, for items that do not hold a
	 * primitive value.
	 */
	String strVal1;

	/**
	 * Second part of the value of this item, for items that do not hold a
	 * primitive value.
	 */
	String strVal2;

	/**
	 * Third part of the value of this item, for items that do not hold a
	 * primitive value.
	 */
	String strVal3;

	/**
	 * The hash code value of this constant pool item.
	 */
	int hashCode;

	/**
	 * Link to another constant pool item, used for collision lists in the
	 * constant pool's hash table.
	 */
	Item next;

	/**
	 * Constructs an uninitialized {@link Item}.
	 */
	Item() {
	}

	/**
	 * Constructs an uninitialized {@link Item} for constant pool element at
	 * given position.
	 *
	 * @param index index of the item to be constructed.
	 */
	Item(final int index) {
		this.index = index;
	}

	/**
	 * Constructs a copy of the given item.
	 *
	 * @param index index of the item to be constructed.
	 * @param i     the item that must be copied into the item to be constructed.
	 */
	Item(final int index, final Item i) {
		this.index = index;
		type = i.type;
		intVal = i.intVal;
		longVal = i.longVal;
		strVal1 = i.strVal1;
		strVal2 = i.strVal2;
		strVal3 = i.strVal3;
		hashCode = i.hashCode;
	}

	/**
	 * Sets this item to an integer item.
	 *
	 * @param intVal the value of this item.
	 */
	void set(final int intVal) {
		this.type = ClassWriter.INT;
		this.intVal = intVal;
		this.hashCode = 0x7FFFFFFF & (type + intVal);
	}

	/**
	 * Sets this item to a long item.
	 *
	 * @param longVal the value of this item.
	 */
	void set(final long longVal) {
		this.type = ClassWriter.LONG;
		this.longVal = longVal;
		this.hashCode = 0x7FFFFFFF & (type + (int) longVal);
	}

	/**
	 * Sets this item to a float item.
	 *
	 * @param floatVal the value of this item.
	 */
	void set(final float floatVal) {
		this.type = ClassWriter.FLOAT;
		this.intVal = Float.floatToRawIntBits(floatVal);
		this.hashCode = 0x7FFFFFFF & (type + (int) floatVal);
	}

	/**
	 * Sets this item to a double item.
	 *
	 * @param doubleVal the value of this item.
	 */
	void set(final double doubleVal) {
		this.type = ClassWriter.DOUBLE;
		this.longVal = Double.doubleToRawLongBits(doubleVal);
		this.hashCode = 0x7FFFFFFF & (type + (int) doubleVal);
	}

	/**
	 * Sets this item to an item that do not hold a primitive value.
	 *
	 * @param type    the type of this item.
	 * @param strVal1 first part of the value of this item.
	 * @param strVal2 second part of the value of this item.
	 * @param strVal3 third part of the value of this item.
	 */
	@SuppressWarnings("fallthrough")
	void set(final int type, final String strVal1, final String strVal2,
			 final String strVal3) {
		this.type = type;
		this.strVal1 = strVal1;
		this.strVal2 = strVal2;
		this.strVal3 = strVal3;
		switch (type) {
			case ClassWriter.CLASS:
				this.intVal = 0;     // intVal of a class must be zero, see visitInnerClass
			case ClassWriter.UTF8:
			case ClassWriter.STR:
			case ClassWriter.MTYPE:
			case ClassWriter.MODULE:
			case ClassWriter.PACKAGE:
			case ClassWriter.TYPE_NORMAL:
				hashCode = 0x7FFFFFFF & (type + strVal1.hashCode());
				return;
			case ClassWriter.NAME_TYPE: {
				hashCode = 0x7FFFFFFF & (type + strVal1.hashCode()
						* strVal2.hashCode());
				return;
			}
			// ClassWriter.FIELD:
			// ClassWriter.METH:
			// ClassWriter.IMETH:
			// ClassWriter.HANDLE_BASE + 1..9
			default:
				hashCode = 0x7FFFFFFF & (type + strVal1.hashCode()
						* strVal2.hashCode() * strVal3.hashCode());
		}
	}

	/**
	 * Sets the item to an InvokeDynamic item.
	 *
	 * @param name     invokedynamic's name.
	 * @param desc     invokedynamic's desc.
	 * @param bsmIndex zero based index into the class attribute BootrapMethods.
	 */
	void set(String name, String desc, int bsmIndex) {
		this.type = ClassWriter.INDY;
		this.longVal = bsmIndex;
		this.strVal1 = name;
		this.strVal2 = desc;
		this.hashCode = 0x7FFFFFFF & (ClassWriter.INDY + bsmIndex
				* strVal1.hashCode() * strVal2.hashCode());
	}

	/**
	 * Sets the item to a BootstrapMethod item.
	 *
	 * @param position position in byte in the class attribute BootrapMethods.
	 * @param hashCode hashcode of the item. This hashcode is processed from the
	 *                 hashcode of the bootstrap method and the hashcode of all
	 *                 bootstrap arguments.
	 */
	void set(int position, int hashCode) {
		this.type = ClassWriter.BSM;
		this.intVal = position;
		this.hashCode = hashCode;
	}

	/**
	 * Indicates if the given item is equal to this one. <i>This method assumes
	 * that the two items have the same {@link #type}</i>.
	 *
	 * @param i the item to be compared to this one. Both items must have the
	 *          same {@link #type}.
	 * @return <tt>true</tt> if the given item if equal to this one,
	 * <tt>false</tt> otherwise.
	 */
	boolean isEqualTo(final Item i) {
		switch (type) {
			case ClassWriter.UTF8:
			case ClassWriter.STR:
			case ClassWriter.CLASS:
			case ClassWriter.MODULE:
			case ClassWriter.PACKAGE:
			case ClassWriter.MTYPE:
			case ClassWriter.TYPE_NORMAL:
				return i.strVal1.equals(strVal1);
			case ClassWriter.TYPE_MERGED:
			case ClassWriter.LONG:
			case ClassWriter.DOUBLE:
				return i.longVal == longVal;
			case ClassWriter.INT:
			case ClassWriter.FLOAT:
				return i.intVal == intVal;
			case ClassWriter.TYPE_UNINIT:
				return i.intVal == intVal && i.strVal1.equals(strVal1);
			case ClassWriter.NAME_TYPE:
				return i.strVal1.equals(strVal1) && i.strVal2.equals(strVal2);
			case ClassWriter.INDY: {
				return i.longVal == longVal && i.strVal1.equals(strVal1)
						&& i.strVal2.equals(strVal2);
			}
			// case ClassWriter.FIELD:
			// case ClassWriter.METH:
			// case ClassWriter.IMETH:
			// case ClassWriter.HANDLE_BASE + 1..9
			default:
				return i.strVal1.equals(strVal1) && i.strVal2.equals(strVal2)
						&& i.strVal3.equals(strVal3);
		}
	}

}
